I want to make a wifi router for both ethernet => wifi and wifi => wifi from my Raspberry 4 B.
I installed OpenWrt with success and it works, but for the latter case I need a second wifi port. So I purchased a TP-Link Archer T3U USB Wifi dongle and plugged it into a USB 2 port of the RPI.
But iti did not work and finding drivers (e.g. Realtek 8812BU) only leads to shady source code packages without a decent installation manual and no ready to use drivers. So I decided to return it to the shop.
Is there another Wifi USB dongle which works out of the box on a RPI 4B using OpenWrt OS ?
I have OpenWrt OS 22.03.
With 'out of the box' I mean at least with precompiled drivers ready to install.
TP-link UE300 is a wired Ethernet adapter.
What I need is a USB Wifi dongle to add an extra wifi port to the Raspberry Pi with OpenWrt to use it as a wifi to wifi router with its own subnet.
The intended use is a travel router, so connecting the 'front end' of the RPI to the public wifi and the 'back end' is an isolated subnet.
The claim is made on this page that the COMFAST CF-951AX works with the Raspberry Pi 4, but you have to connect it with a USB "angle adapter". Plugging it in straight will block other ports, and plugging it in with a USB extension cable won't work.
The chip is the mt7921au, which is supported in-kernel.
Is there a kernel module for the mt7921au in OpenWRT 22.03? No. But maybe there's one in OpenWRT 23.05.
I've seen this adapter for sale locally in the country where I am located. It's a mid-range price, for this market.
Have I tested this dongle myself in OpenWRT, or anywhere? No.
These are the plausible-sounding drivers that are available in OpenWRT 23.05, but I'm not sure if any of these provide support to the mt7921au chipset:
kmod-mt7921e
kmod-mt7921s
kmod-mt7921u
According to this post, the kmod-mt7921u module looks like it might work.
I have Comfast CF-953AX (which is same chipset as CF-951AX but different form factor), and just tested with my Linksys WRT1900ACv2 on 23.05.0, installed kmod-mt7921u and it works! Now there is an usable AX AP on my router (by the time I am typing this, I am also using this setup for video conference)
EDIT: Not sure if this is issue with Linksys or the Comfast dongle, when I run a speedtest with very high throughput on it my router hangs.
I found that it's not the problem of my Linksys router, because trying with NanoPi R6S with mj2222's kernel 6.1 build I am having same problem, the AP mode started and then after getting a large amount of traffic on it the WiFi will crash with following kernel message:
The router itself doesn't hang because cable connectivity is still working great, I can restart WiFi manually, or I waited ~3mins then I observed the WiFi reloads.
For my Raspberry PI 4 config I decided to not use a wifi dongle but bought a https://store.ui.com/us/en/products/u6-lite that allowed me to place the radio in a better location. Have been fast and extremely stable.
Apparently that U6 Lite is powered by POE. Did you have to also buy a POE hat for your RPi?
BTW: It's for sale in my market, but a little too pricey for me. None the less, thanks for the recommendation!
Another concern I have there is that the U6 Lite consumes at max, 12W. But only 5ish Watts can be delivered by an Rpi4. Is the power sufficient for the U6 Lite? Does it ever complain about undervolting, somehow?
The U6 Lite might not get all the juice it's wanting, without using, say, an RPi5, which can deliver considerably more Watts to peripherals with their new 37W power supply. Or maybe you just have a POE-capable switch.
In this Network Chuck video, he's using a cheap Mediatek RT5370-based USB dongle. That older dongle has 2.4GHz only (no 5GHz,) and has only 802.11n (not 802.11ac or above).
If I'm not mistaken, nobody on this forum has been able to reproduce his success with that kind of dongle on an RPi4, however.
These very generically-branded dongles are still on sale for super cheap in my market.
Has anyone had any stable performance out of Mediatek RT5370 dongles connected to an RPi4? You know, other than Network Chuck?
USB WLAN cards aren't great for this purpose to begin with, but do yourself a favour and skip rt2x00 based (old) chipsets with more contemporary mt76 based ones instead, hardware and drivers have made a huge leap forward, especially for the less common modes of operation (e.g. AP mode).
I'm still a strong proponent of outsourcing wireless to purpose-built hardware (cheap OpenWrt supported wireless routers/ APs) or at least Mediatek/ QCA PCIe cards (functionally fine, just rare, expensive and with rather high requirements on the host board <-- power consumption/ cooling), 15 bucks for an mt7621a+mt7915DBDC AP get you much further than any (set of) USB WLAN card(s).
I have a comfast CF-951AX and only work stable when is connected to USB 2.0 ports, mt7921u have a temp sensor, I had observed when the adapter is connected to USB 3.0 ports temp rises about 75°C and crash.
What's the rough room temperature when that happens, on the hot side or does the chip heat itself up that much?
From a technical point of view, USB 2.0 is not sufficient to max out the performance of 802.11ax (and it probably won't deliver enough power either), so it's not surprising that the device (can) stay cooler, but it's made to be used with USB 3.0 to achieve full performance (but thermal design has to cope with that under full load).
I'm not at all surprised that these cards are 'running hot', but the devices just need to be designed in a way to cope with that - and not crash.
I was thinking about lower down the speed so I later picked a Samsung phone with only 802.11ac 2x2 support to test with it, the speed was around 600-700Mbps however after 2-3 rounds of speed test it simply crashes.
And right now the room temperature is ~20C which is not hot at all.
